Spectroscopic Characterization of Nanoscale Modification of Passivated Si(100) Surface by STM

1994 ◽  
Vol 332 ◽  
Author(s):  
F. PÉRez-Murano ◽  
N. Barniol ◽  
X. Aymerich
Keyword(s):  
Local Density ◽  
Surface States ◽  
Spectroscopic Characterization ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Band Bending ◽  
Sample Spacing ◽  
Current Voltage

ABSTRACTThe electrochemical modification of H-passivated Si(100) surface is produced and characterized by Scanning Tunneling Microscopy and Spectroscopy (STM/STS) operating in air. In order to better understand this nanometer scale modification, we have characterized spectroscopically the modified region. From the current-voltage (I/V) curves, dI/dV versus V curves and tip to sample spacing versus voltage (s/V) curves (at constant current) we have concluded that the modification induces a local electrochemical change on the surface, which in turn produces both, a decrease of the local density of surface states and a variation of the band bending in the silicon surface.

In-Plane Asymmetries on the Ge(111)-c(2×8) Surface Mapped with the Scanning Tunneling Microscope

1992 ◽  
Vol 295 ◽  
Author(s):  
P. Molinàs-Mata ◽  
J. Zegenhagen ◽  
M. Böhringer ◽  
N. Takeuchi ◽  
A. Selloni
Keyword(s):  
Local Density ◽  
Experimental Studies ◽  
Surface States ◽  
Small Sample ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron ◽  
Tunneling Currents ◽  
Insight Into

AbstractWe report on new experimental studies of the Ge(111)-c(2×8) reconstruction performed with low-energy electron diffraction. (LEED) and scanning tunneling microscopy (STM). Weak quarter-order reflections are present in the c(2 × 8) LEED pattern in agreement with previous observations and results of ab initio calculations. In order to gain insight into the predicted splitting of dangling bond states, we compare constant current topographs (CCT's) performed at high-tunneling currents (40.nA) with first-principles calculations of the local density of states (LDOS) 1Å above the surface adatoms and obtain good qualitative agreement. We finally discuss to what extent the STM CCT's at high tunneling currents (small sample-tip distances (STD)) are sensitive to surface states outside the Г point.

Scanning Tunneling Microscopy Imaging and Spectroscopy of a Single Viologen Molecule

2008 ◽  
Vol 8 (9) ◽  
pp. 4621-4625
Author(s):  
Nam-Suk Lee ◽  
Chang-Heon Yang ◽  
Won-Suk Choi ◽  
Young-Soo Kwon
Keyword(s):  
Self Assembly ◽  
Current Mode ◽  
Scanning Tunneling Spectroscopy ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Microscopy Imaging ◽  
Current Voltage ◽  
Imaging And Spectroscopy ◽  
Stm Images

A low-temperature ultrahigh-vacuum scanning tunneling microscope (UHV-STM) was used to image viologen (N-methyl-N′-di (8-mercaptooctyl)-4,4′-bipyridinium; HSC8VC8SH) molecules and to perform local spectroscopic measurements on these molecules. Self-assembly of viologen molecules was conducted on Au (111), which had been thermally deposited onto freshly cleaved, heated mica. Here, we demonstrate a novel SAM matrix appropriate for the isolation of viologen molecules composed of octanethiol (C8) in which HSC8VC8SH was inserted at defects in the molecular lattice. The isolated single molecules of viologen inserted in the SAM matrix were observed as protrusions in STM topography using a constant current mode. STM images at 298 K showed protrusions with a topographic height of about 2.71 nm (HSC8VC8SH) with viologen molecules that self-assembled on the substrate. The current–voltage (I–V) characteristics were measured while the electrical properties of the formed monolayer were scanned using scanning tunneling spectroscopy (STS). We found the high peak current-like rectification at +1.14 V (HSC8VC8SH). The rectification ratios, RR = J (at +2.5 V)/J (at −2.5 V), are in the range of 4.47.

scholarly journals Comprehensive Electrostatic Modeling of Exposed Quantum Dots in Graphene/Hexagonal Boron Nitride Heterostructures

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1154
Author(s):  
Eberth A. Quezada-López ◽  
Zhehao Ge ◽  
Takashi Taniguchi ◽  
Kenji Watanabe ◽  
Frédéric Joucken ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Boron Nitride ◽  
Local Density ◽  
Hexagonal Boron Nitride ◽  
Tight Binding ◽  
Spectroscopic Characterization ◽  
Scanning Tunneling ◽  
Klein Tunneling ◽  
Electrostatic Modeling

Recent experimental advancements have enabled the creation of tunable localized electrostatic potentials in graphene/hexagonal boron nitride (hBN) heterostructures without concealing the graphene surface. These potentials corral graphene electrons yielding systems akin to electrostatically defined quantum dots (QDs). The spectroscopic characterization of these exposed QDs with the scanning tunneling microscope (STM) revealed intriguing resonances that are consistent with a tunneling probability of 100% across the QD walls. This effect, known as Klein tunneling, is emblematic of relativistic particles, underscoring the uniqueness of these graphene QDs. Despite the advancements with electrostatically defined graphene QDs, a complete understanding of their spectroscopic features still remains elusive. In this study, we address this lapse in knowledge by comprehensively considering the electrostatic environment of exposed graphene QDs. We then implement these considerations into tight binding calculations to enable simulations of the graphene QD local density of states. We find that the inclusion of the STM tip’s electrostatics in conjunction with that of the underlying hBN charges reproduces all of the experimentally resolved spectroscopic features. Our work provides an effective approach for modeling the electrostatics of exposed graphene QDs. The methods discussed here can be applied to other electrostatically defined QD systems that are also exposed.

Cross-Sectional Scanning Tunneling Microscopy of III-V Heterostructures Grown by Molecular-Beam Epitaxy

1994 ◽  
Vol 340 ◽  
Author(s):  
A.Y. Lew ◽  
E.T. Yu ◽  
D.H. Chow ◽  
R.H. Miles
Keyword(s):  
Molecular Beam Epitaxy ◽  
Scanning Tunneling Microscopy ◽  
Molecular Beam ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Close Inspection ◽  
Cross Sectional ◽  
Current Voltage ◽  
Strained Layer Superlattices

ABSTRACTCross-sectional scanning tunneling microscopy and spectroscopy have been used to characterize InAs/Ga1-x InxSb strained-layer superlattices grown by molecular-beam epitaxy. Atomic-resolution constant-current images of the epitaxial layers reveal monolayer roughness at the superlattice interfaces. An asymmetry in electronic structure between interfaces in which InAs has been grown on Ga1-x InxSb and those in which Ga1-x InxSb has been grown on InAs has also been observed in these images. Close inspection of the images reveals increased growthdirection lattice spacings in the Ga1-x InxSb layers compared to the InAs layers, as well as even larger lattice spacings at the InAs/Ga1-x InxSb interfaces. The latter is consistent with the formation of primarily InSb-like interfaces. Current-voltage spectra obtained while tunneling into the superlattice layers are found to be strongly influenced by extended superlattice electronic states.

Scanning tunneling microscopy of polymers: A status report

1989 ◽  
Vol 47 ◽  
pp. 330-331
Author(s):  
P.E. Russell ◽  
I.H. Musselman
Keyword(s):  
High Resolution ◽  
Scanning Tunneling Microscopy ◽  
Sample Surface ◽  
Atomic Scale ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Status Report ◽  
Tunneling Microscopy ◽  
Research Issues ◽  
Wide Range

Scanning tunneling microscopy (STM) has evolved rapidly in the past few years. Major developments have occurred in instrumentation, theory, and in a wide range of applications. In this paper, an overview of the application of STM and related techniques to polymers will be given, followed by a discussion of current research issues and prospects for future developments. The application of STM to polymers can be conveniently divided into the following subject areas: atomic scale imaging of uncoated polymer structures; topographic imaging and metrology of man-made polymer structures; and modification of polymer structures. Since many polymers are poor electrical conductors and hence unsuitable for use as a tunneling electrode, the related atomic force microscopy (AFM) technique which is capable of imaging both conductors and insulators has also been applied to polymers.The STM is well known for its high resolution capabilities in the x, y and z axes (Å in x andy and sub-Å in z). In addition to high resolution capabilities, the STM technique provides true three dimensional information in the constant current mode. In this mode, the STM tip is held at a fixed tunneling current (and a fixed bias voltage) and hence a fixed height above the sample surface while scanning across the sample surface.

Electronic trap characterization of the Sc2O3∕La2O3 high-κ gate stack by scanning tunneling microscopy

2008 ◽  
Vol 92 (2) ◽  
pp. 022904 ◽  
Author(s):  
Y. C. Ong ◽  
D. S. Ang ◽  
K. L. Pey ◽  
Z. R. Wang ◽  
S. J. O’Shea ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Gate Stack

Manufacturing and Characterization of Nanostructures Using Scanning Tunneling Microscopy with Diamond Tip

2016 ◽  
Vol 42 ◽  
pp. 14-46 ◽  
Author(s):  
Oleg G. Lysenko ◽  
Vladimir I. Grushko ◽  
Sergey N. Dub ◽  
Eugene I. Mitskevich ◽  
Nikolay V. Novikov ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Measuring System ◽  
Scanning Tunneling ◽  
Surface Load ◽  
Tunneling Microscopy ◽  
Electromagnetic Probe ◽  
High Pressure High Temperature ◽  
Single Crystal Diamond ◽  
Selection Of

Nanoscale experiments with diamond tip that include processing, visualization and tunneling spectroscopy of the surface are presented. Single crystal diamond synthesized by the temperature gradient method under high pressure–high temperature (HPHT) conditions is proposed as a multifunctional tip for scanning tunneling microscopy (STM). Sequence of the procedures covering growing crystals with predetermined physical properties, selection of the synthesized crystals with the desired habit and their precise shaping have been developed. The original STM’s peculiarity is the electromagnetic probe-to-surface load measuring system. The results of fabrication and characterization of nanostructures for nanoelectronics, data storages and biology are demonstrated and discussed.

Sign in / Sign up

Export Citation Format

Share Document